The smallest breach of a primary reactor system has the potential of causing major problems. The water and steam associated with the reactor carry radioactive materials which are very hazardous to human health. Atomic bomb type explosions are not possible because there is not enough plutonium or other fissionable material in the reactor to cause such an explosion.
The primary purpose of the invention is to isolate the troubled area in a few seconds either automatically or with human intervention. To accomplish this, large quantities of sand and boron powder are placed above the area to be protected and upon occurrence of an emergency, e.g., an explosion in the reactor room gravity is used to deliver these substances into the endangered area in less than five seconds. Provision is made to delay this delivery for a few seconds if human life is endangered, but it can only be held up for a few predetermined seconds. After this, the equipment starts its operation automatically.
It has been suggested heretofore that protection from undesirable radiation can be obtained by locating the reactor room underground, with some of the power generating equipment that is associated with the reactor being located on the ground surface and connected to the reactor by pipes which pass from the ground surface to the underground reactor room. One such arrangement is disclosed, for example, in Lindsley U.S. Pat. No. 3,755,076 issued Aug. 28, 1973, for "Nuclear Powered Energy Conversion System". Another arrangement which employs an underground reactor is disclosed in Schabert U.S. Pat. No. 4,297,167 issued Oct. 27, 1981, for "Nuclear Reactor Installation". Gaiser U.S. Pat. No. 4,483,790 issued Nov. 20, 1984, describes methods for disposing of a shut-down above-ground nuclear reactor by encapsulating the reactor, sinking the encapsulated reactor into an underground pit, and then covering the sunken reactor with earth.
While the foregoing references rely upon the provision of a body of earth between an underground chamber and the ground surface to provide a radiation shield, they do not provide the level of protection which is truly necessary to protect persons from radiation contamination or pollution in the event of a serious accident. In the Lindsley system, for example, the underground reactor chamber communicates with the earth surface via one or more open vertical conduits through which radiation can pass to the earth surface in the event of an accident such as an earthquake, or a reactor explosion; and no provision is made for automatically covering in a few seconds the regions through which such contamination may emanate in the event of such an accident. The present invention is intended to obviate these defects in the prior art by means of a nuclear power plant installation design which provides increased safety.